Clang warns:
drivers/clk/ralink/clk-mtmips.c:309:9: error: variable 'ret' is uninitialized when used here [-Werror,-Wuninitialized]
309 | return ret;
| ^~~
drivers/clk/ralink/clk-mtmips.c:285:9: note: initialize the variable 'ret' to silence this warning
285 | int ret, i;
| ^
| = 0
drivers/clk/ralink/clk-mtmips.c:359:9: error: variable 'ret' is uninitialized when used here [-Werror,-Wuninitialized]
359 | return ret;
| ^~~
drivers/clk/ralink/clk-mtmips.c:335:9: note: initialize the variable 'ret' to silence this warning
335 | int ret, i;
| ^
| = 0
2 errors generated.
Set ret to the return value of clk_hw_register_fixed_rate() using the
PTR_ERR() macro, which ensures ret is not used uninitialized, clearing
up the warning.
Fixes: 6f3b15586e ("clk: ralink: add clock and reset driver for MTMIPS SoCs")
Closes: https://github.com/ClangBuiltLinux/linux/issues/1879
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Until now, clock related code for old ralink SoCs was based in fixed clocks
using 'clk_register_fixed_rate' and 'clkdev_create' directly doing in code
and not using device tree at all for their definition. Including this driver
is an effort to be able to define proper clocks using device tree and also
cleaning all the clock and reset related code from 'arch/mips/ralink' dir.
This clock and reset driver covers all the ralink SoCs but MT7621 which is
the newest and provides gating and some differences that make it different
from its predecesors. It has its own driver since some time ago. The ralink
SoCs we are taking about are RT2880, RT3050, RT3052, RT3350, RT3352, RT3883,
RT5350, MT7620, MT7628 and MT7688. Mostly the code in this new driver has
been extracted from 'arch/mips/ralink' and cleanly put using kernel clock
driver APIs. The clock plans for this SoCs only talks about relation between
CPU frequency and BUS frequency. This relation is different depending on the
particular SoC. CPU clock is derived from XTAL frequencies.
Depending on the SoC we have the following frequencies:
* RT2880 SoC:
- XTAL: 40 MHz.
- CPU: 250, 266, 280 or 300 MHz.
- BUS: CPU / 2 MHz.
* RT3050, RT3052, RT3350:
- XTAL: 40 MHz.
- CPU: 320 or 384 MHz.
- BUS: CPU / 3 MHz.
* RT3352:
- XTAL: 40 MHz.
- CPU: 384 or 400 MHz.
- BUS: CPU / 3 MHz.
- PERIPH: 40 MHz.
* RT3383:
- XTAL: 40 MHz.
- CPU: 250, 384, 480 or 500 MHz.
- BUS: Depends on RAM Type and CPU:
+ RAM DDR2: 125. ELSE 83 MHz.
+ RAM DDR2: 128. ELSE 96 MHz.
+ RAM DDR2: 160. ELSE 120 MHz.
+ RAM DDR2: 166. ELSE 125 MHz.
* RT5350:
- XTAL: 40 MHz.
- CPU: 300, 320 or 360 MHz.
- BUS: CPU / 3, CPU / 4, CPU / 3 MHz.
- PERIPH: 40 MHz.
* MT7628 and MT7688:
- XTAL: 20 MHz or 40 MHz.
- CPU: 575 or 580 MHz.
- BUS: CPU / 3.
- PCMI2S: 480 MHz.
- PERIPH: 40 MHz.
* MT7620:
- XTAL: 20 MHz or 40 MHz.
- PLL: XTAL, 480, 600 MHz.
- CPU: depends on PLL and some mult and dividers.
- BUS: depends on PLL and some mult and dividers.
- PERIPH: 40 or XTAL MHz.
MT7620 is a bit more complex deriving CPU clock from a PLL and an bunch of
register reads and predividers. To derive CPU and BUS frequencies in the
MT7620 SoC 'mt7620_calc_rate()' helper is used.
In the case XTAL can have different frequencies and we need a different
clock frequency for peripherals 'periph' clock in introduced.
The rest of the peripherals present in the SoC just follow their parent
frequencies.
With this information the clk driver will provide all the clock and reset
functionality from a set of hardcoded clocks allowing to define a nice
device tree without fixed clocks.
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Compiling clock driver with CONFIG_UBSAN enabled shows the following trace:
UBSAN: shift-out-of-bounds in drivers/clk/ralink/clk-mt7621.c:121:15
shift exponent 131072 is too large for 32-bit type 'long unsigned int'
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.15.86 #0
Stack : ...
Call Trace:
[<80009a58>] show_stack+0x38/0x118
[<8045ce04>] dump_stack_lvl+0x60/0x80
[<80458868>] ubsan_epilogue+0x10/0x54
[<804590e0>] __ubsan_handle_shift_out_of_bounds+0x118/0x190
[<804c9a10>] mt7621_gate_is_enabled+0x98/0xa0
[<804bb774>] clk_core_is_enabled+0x34/0x90
[<80aad73c>] clk_disable_unused_subtree+0x98/0x1e4
[<80aad6d4>] clk_disable_unused_subtree+0x30/0x1e4
[<80aad6d4>] clk_disable_unused_subtree+0x30/0x1e4
[<80aad900>] clk_disable_unused+0x78/0x120
[<80002030>] do_one_initcall+0x54/0x1f0
[<80a922a4>] kernel_init_freeable+0x280/0x31c
[<808047c4>] kernel_init+0x20/0x118
[<80003e58>] ret_from_kernel_thread+0x14/0x1c
Shifting a value (131032) larger than the type (32 bit unsigned integer)
is undefined behaviour in C.
The problem is in 'mt7621_gate_is_enabled()' function which is using the
'BIT()' kernel macro with the bit index for the clock gate to check if the
bit is set. When the clock gates structure is created driver is already
setting 'bit_idx' using 'BIT()' macro, so we are wrongly applying an extra
'BIT()' mask here. Removing it solve the problem and makes this function
correct. However when clock gating is correctly working, the kernel starts
disabling those clocks that are not requested. Some drivers for this SoC
are older than this clock driver itself. So to avoid the kernel to disable
clocks that have been enabled until now, we must apply 'CLK_IS_CRITICAL'
flag on gates initialization code.
Fixes: 48df7a26f4 ("clk: ralink: add clock driver for mt7621 SoC")
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20230206083305.147582-1-sergio.paracuellos@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
MT7621 system controller node is already providing the clocks for the whole
system but must also serve as a reset provider. Hence, add reset controller
related code to the clock driver itself. To get resets properly ready for
the rest of the world we need to move platform driver initialization process
to 'arch_initcall'.
CC: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20220210094859.927868-3-sergio.paracuellos@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
'clk_init_data' for gates is setting up 'CLK_IS_CRITICAL'
flag for all of them. This was being doing because some
drivers of this SoC might not be ready to use the clock
and we don't wanted the kernel to disable them since default
behaviour without clock driver was to set all gate bits to
enabled state. After a bit more testing and checking driver
code it is safe to remove this flag and just let the kernel
to disable those gates that are not in use. No regressions
seems to appear.
Fixes: 48df7a26f4 ("clk: ralink: add clock driver for mt7621 SoC")
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20210727055537.11785-1-sergio.paracuellos@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
The documentation for this SOC only talks about two
registers regarding to the clocks:
* SYSC_REG_CPLL_CLKCFG0 - provides some information about
boostrapped refclock. PLL and dividers used for CPU and some
sort of BUS.
* SYSC_REG_CPLL_CLKCFG1 - a banch of gates to enable/disable
clocks for all or some ip cores.
Looking into driver code, and some openWRT patched there are
another frequencies which are used in some drivers (uart, sd...).
According to all of this information the clock plan for this
SoC is set as follows:
- Main top clock "xtal" from where all the rest of the world is
derived.
- CPU clock "cpu" derived from "xtal" frequencies and a bunch of
register reads and predividers.
- BUS clock "bus" derived from "cpu" and with (cpu / 4) MHz.
- Fixed clocks from "xtal":
* "50m": 50 MHz.
* "125m": 125 MHz.
* "150m": 150 MHz.
* "250m": 250 MHz.
* "270m": 270 MHz.
We also have a buch of gate clocks with their parents:
* "hsdma": "150m"
* "fe": "250m"
* "sp_divtx": "270m"
* "timer": "50m"
* "pcm": "270m"
* "pio": "50m"
* "gdma": "bus"
* "nand": "125m"
* "i2c": "50m"
* "i2s": "270m"
* "spi": "bus"
* "uart1": "50m"
* "uart2": "50m"
* "uart3": "50m"
* "eth": "50m"
* "pcie0": "125m"
* "pcie1": "125m"
* "pcie2": "125m"
* "crypto": "250m"
* "shxc": "50m"
With this information the clk driver will provide clock and gates
functionality from a a set of hardcoded clocks allowing to define
a nice device tree without fixed clocks.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20210410055059.13518-2-sergio.paracuellos@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
